Pharmaceutical solids can exist in different forms, such as crystalline, amorphous, or glass and also in solvated or hydrated forms. A polymorph is a solid crystalline phase of a compound resulting from the possibility of at least two crystalline arrangements of the molecules of that compound in the solid state.
It is a well known fact that different forms of the same drug may provide differences in certain pharmaceutically important physicochemical properties, such as stability, solubility, dissolution rate, crystal habit and tableting behavior. Changes in certain of these physiochemical properties may ultimately affect the bioavailability of the drug.
Picropodophyllin is a compound belonging to the class of compounds denominated cyclolignans, having the chemical structure:

For a long time, picropodophyllin attracted little interest, since it was believed to possess no or low biological activity. In contrast, its stereoisomer podophyllotoxin, which has a trans configuration in the lactone ring, has been studied for decades due to its cytotoxic properties.

However, research has proven that picropodophyllin exhibits interesting biological properties and hence potential as a medicament.
WO 02/102804 discloses that picropodophyllin is a specific and potent inhibitor of insulin-like growth factor-1 receptor (IGF-1R) and may be useful in the treatment of IGF-1R dependent diseases such as various types of cancer, artheriosclerosis, psoriasis, and restenosis following coronary angioplasty.
WO 2007/097707 discloses the use of picropodophyllin in the prophylaxis or treatment of diabetes mellitus type 2, nephropathy, retinopathy, macular degeneration, retinopathy of prematurity, central retinal vein occlusion, branch retinal vein occlusion, rubeotic glaucoma, thyroid eye disease, corneal graft rejection and corneal chemical burns; and for contraception.
WO 2009/157858 discloses the use of picropodophyllin for the prophylaxis or treatment of diseases or conditions characterized by a hyperactive immune system such as rheumatoid arthritis, Crohn's disease, ulcerative colitis, multiple sclerosis, Alzheimer's disease, asthma, eczematous dermatitis, and graft rejection following transplantation.
Z. Kristallogr. 215 (2000) pp. 45-47 discloses a crystalline structure of picropodophyllin for which crystal data are reported.
Picropodophyllin monohydrate and picropodophyllin polymorph A are disclosed by Schrecker et al in Helvetica Chimica Acta (1954); 37; pp. 1541-1543.